Zhang, M. (Corresponding author)FZJ*

2006
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Report No.: Juel-4235

Abstract: As continued MOSFETs scaling becomes increasingly challenging, solutions are urgently needed to meet the requirements of the ITRS roadmap. Schottky barrier-MOSFETs are promising alternative devices to current conventional MOSFET because the metallic source/drain contacts has many inherent advantages . However, generally Schottky barrier-MOSFET devices exhibit an inferior performance due to the high Schottky barrier at the source/drain contacts. In order to overcome this problem, lowering of the effective Schottky barrier of nickel silicide was investigated by dopant segregation at the silicide/Si interface, by the use of ultra-thin gate oxide and ultra-thin body SOI. Modelling of single-gated, fully depleted ballistic SOI Schottky barrier-MOSFET were performed with a self-consistent solution of the one-dimensional modified Poisson and Schroedinger equations. An essential difference be tween Schottky barrier and conventional MOSFET is that tunneling currents through the Schottky barriers play a crucial role. The simulation results show that the Schottky barrier width is strongly influenced by geometrical parameters, i.e., the thinner the gate oxide and the Si channel, the lower the effective Schottky barrier height. Devices with a few nanometers spatially extended highly doped layer directly at the simulated silicide/Si channel interface has a further improved inverse subthreshold slope close to the thermal limit 60mV/dec. In addition, the on-currents were significantly increased. The reason for the dramatic improvement is that the conduction/valence bands are strongly bent due to the highly doped layer and hence the Schottky barriers for electrons becomes highly transparent resulting in an improved on-as well as off-currents. Before transforming this concept on the device, we investigated the fabrication of nickel silicide on ultra-thin SOI ($\thicksim$ 10nm) and the effect of silicidation induced dopant segregation on diode characteristics. Experimental results show that fully silicided nickel silicide on SOI has a low specific resistivity of 16-20 $\mu \Omega$cm. In addition, we observed that a high concentration of As/B segregated at the interface of nickel silicide and Si which lowers [...]

1. Halbleiter-Nanoelektronik (IBN-1)